Coating machine

ABSTRACT

A machine, that incorporates an applicating mechanism, for applying coating material to a portion of the vamp of a shoe upper to form a box toe. The applicating mechanism includes a roll rotatable within a housing between a pair of walls, the bottom of one of the walls constituting a scraper blade. The movement of the vamp beneath the applicating mechanism causes the roll to apply the coating material to the vamp to a thickness determined by the scraper blade.

D United States Patent 1151 3,653,356

Brastow [4 1 Apr. 4, 1972 [54] COATING MACHINE 3,272,177 9/1966 Kelley...'. ..118/202 2,303,171 11/1942 Morrison 1 18/261 [72] Bmsmw Mass 3,277,867 10/1966 Kilham et al ..1 l8/204 [73] Assignee: Jacob S. Kamborian, West Newton, Mass.

. 1 Primary ExaminerMervin Stein t. 2 [22] Ffled Sap 1970 Assistant Examiner-Leo Millstein PP 69,069 Attomey-Albert Gordon 52 U.S. c1 ..118/7, 118/202, 118/204, [57] ABSTRACT 8/238, 8 261 A machine, that incorporates an applicating mechanism, for [51] hit. Cl. ..B05c 11/00 applying coating material to a portion of the vamp of a shoe Fleld 0 Search 6, pp to f a box toe T ppli i g mechanism includes 8/204 a roll rotatable within a housing between a pair of walls, the bottom of one of the walls constituting a scraper blade. The [56] v References cned movement of the vamp beneath the applicating mechanism UNITED STA-[ES PATENTS causes the roll to apply the coating material tothe vamp to a thickness determined by the scraper blade. 3,359,939 12/1967 Von Schoppe ..118/202 2,642,032 6/1953 6 Claims, 9 Drawing Figures Osgood ..118/261 PATENTEBAFR 4 I972 SHEET 3 [IF 6 PATENTEDAPR 4 I87? SHEET 5 0F 6 COATING MACHINE This invention is concerned with the application of a coating to a portion of a workpiece. The workpiece is disclosed as being the vamp or toe portion of a shoe upper whose coating is intended to form a box toe or stiffener.

A machine for applying the coating to the workpiece includes an applicating assembly, constituted by an applicator member and a scraper member that is located forwardly of the applicator member. The workpiece is mounted on a carriage below the applicating assembly for forward-rearward movement and the applicating assembly is mounted for heightwise movement. While the applicating assembly is in an upper position, the carriage, with the workpiece mounted thereon, is moved rearwardly from a front position to a back position. The applicating assembly is then lowered and the carriage is moved from the back position to the front position to enable the applicator member to apply a coating to the workpiece to a thickness determined by the spacing between the scraper member and the workpiece.

It has been found that, in the operation of this machine, blobs of coating material tend to be formed on the scraper member in a machine cycle. If this blob is not wiped off before the commencement of the coating operation in the next machine cycle, the blob can transfer onto the workpiece and adhere to a portion of the workpiece that it is not intended to coat. One aspect of this invention is concerned with an improvement of the machine that enables the blob formed on the scraper member during a coating operation on one workpiece to be wiped off before a coating operation is performed on the next workpiece. This is achieved by incorporating in the machine a mechanism for lowering the applicating assembly after the carriage has commenced its rearward movement and is in an intermediate position between the front and back positions so that any blob on the scraper member is wiped onto a portion of the workpiece that will subsequently be coated.

An applicating mechanism for applying the coating material to the workpiece comprises a housing having a hollow interior defined by a front wall and a back wall. An applicator roll is rotatably mounted in the housing between the walls and is driven in such a manner that its front, which faces the front wall, moves downwardly and its back, which faces the back wall, moves upwardly. With the walls spaced from the roll, coating material supplied to the top of the rotating roll is transferred by the portion of the bottom of the roll that is located between the bottoms of the walls onto a workpiece. When the applicating mechanism is shut off, the roll is caused to cease its rotation and the walls are manually moved into engagement with the roll to thereby trap the coating material in the housing interior above the roll. There is a tendency, with this arrangement, for the coating material to leak from between the walls and the roll when the mechanism is being shut off and to leak downwardly of the roll after the mechanism has been shut off.

A second aspect of the invention is concerned with an improvement in the applicating mechanism which eliminates the leakage of coating material during and after the shutting ofi of the mechanism. This is accomplished by providing an operating member that is operative firstly to move the front wall into engagement with the front of the roll, then to stop the rotation of the roll, and then to move the back wall into engagement with the back of the roll.

In the drawings:

FIG. 1 is a front elevation of the machine;

FIG. 2 is a plan view of the machine;

FIG. 3 is a partially sectional side elevation of the machine;

FIG. 4 is a section taken on the line 44 of FIG. 2;

FIG. 5 is a section taken on the line 5-5 of FIG. 2;

FIG. 6 is a representation of the workpiece and the applicating assembly after the carriage has commenced its rearward movement and before the applicating assembly is lowered;

FIG. 7 is a representation of the workpiece and the applicating assembly when the carriage is in its back position at the completion of its rearward movement;

FIG. 8 is a plan view of the workpiece with the coating applied thereto; and

FIG. 9 is a view taken on the line 9-9 of FIG. 8.

The operator is intended to stand to the left of the machine as seen in FIG. 3. The parts and positions closest to the operator will be designated front and the parts and positions furthermost from the operator will be designated "back." Movements toward the operator will be designated as forwar and movements away from the operator will be designated as rearward.

Referring to FIGS. 1-3, the machine comprises a mount 10 to which are secured a pair of spaced channels l2, 14. A carriage 16 is mounted to the mount 10 for forward-rearward movement by means of rollers 18 that are rotatably mounted to the carriage and are received in the channels 12, 14.

A base 20 is rigidly secured to the carriage 16, and a plate 22 is mounted to the base 20 for heightwise movement. An air-operated motor 24, mounted in the carriage 16, has an upwardly extending piston rod 26 that is adapted to abut against the plate 22 so as to raise it against the force of a plurality of tension springs 28 that are interposed between the plate 22 and the carriage 16. The plate 22 is so constructed that its sides are rearwardly convergent. A block 30 is secured to the top of the plate 22. The sides of the block 30 converge rearwardly similarly to the sides of the plate 22 but are located inwardly of the sides of the plate 22 so as to form a step 32 on the sides of the plate 22. A clamp 34 is secured to the base 20. The sides of the clamp 34, which are located outwardly of the sides of the block 30 and converge rearwardly similarly to the sides of the plate 22 and the block 30, are located above the step 32.

An air-operated motor 36, mounted to a bracket 38 that is secured to and extends upwardly of the mount 10, has a piston rod 40 that is secured to the carriage 16 so as to effect forward-rearward movement of the carriage. A cam 42, mounted to the carriage 16, is in intersecting relationship with a front valve 44 and a back valve 46. The valves 44 and 46 are mounted on the mount 10.

A pair of arms 48 and 50 are pivoted to a rod 52 that is mounted to the bracket 38. An air-operated motor 54 is mounted to the mount 10. The piston rod 56 of the motor 54 is connected to the back of the arm 48. The arms 48 and 50 are connected by a tie rod 58 so that the motor 54 can effect swinging movement of the arms 48 and 50 in unison about the axis of the rod 52.

An applicator roll 60 (see FIGS. 4 and 5) is rotatably mounted to and extends between the arms 48, 50 by means of extensions 61 of the roll that are rotatably mounted in the arms. An electric motor 62 (FIG. 2) is drivingly connected to one of the extensions 61 by a chain 64 and sprockets 66 and 68 to rotate the roll counterclockwise (FIG. 4).

A housing 70 extends between the arms 48, 50 and is pivotally mounted to the arms by pintles 72. The housing 70 has a hollow interior to accommodate the roll 60 which extends between its side walls 74 and 76. The extensions 61 extend through slots 77 (FIG. 5) in the side walls 74 and 76 and seals 79 are interposed between the ends of the roll 60 and the side walls. The front wall 78 of the housing is pivoted to the side walls 74, 76 by pins 80 (FIG. 4). The bottom 81 of the front wall 78 extends downwardly and circumferentially about the roll 60 and terminates in a scraper blade 82. The back wall 84 of the housing 70 is pivoted to the side walls 74, 76 by pins 86. The bottom 88 of the back wall 84 extends towards the roll 60.

The applicator roll 60 and the scraper blade 82 constitute an applicating assembly.

A link 90 (FIG. 4) is pivoted to the housing 70 by a pin 92. The bottom of the link 90 is formed as a clevis 94 that embraces a pin 96 on the front wall 78. A link 98 is pivoted to the housing 70 by a pin 100. The bottom of the link 98 is formed as a clevis 102 that embraces a pin 104 on the back wall 84. A bar 106 is rigidly secured to the link 90 and extends rearwardly thereof alongside the link 98. A pin 108, secured to the bar 106, is in intersecting relationship with the link 98. The front of the link 98 is formed into an abutment surface 110 that lies on an arc whose center of curvature coincides with the axis of the pin 92 and into a slot 112 wide enough to receive the pin 108. The upper and lower surfaces of the slot 112 are located on arcs whose centers of curvature coincide with the axis of the pin 100. The cylinder 114 of an airoperated motor 116 has a block 117 rigidly secured thereto that is pivoted to a clevis 118, and the clevis 118 is rigidly secured to the link 98. The piston rod 120 of the motor 116 is secured to a clevis 122 that is pivoted to the link 90. An electric switch 124, that controls the operation of the motor 62, is mounted to the top of the housing 70 and is in intersecting relationship with a switch actuator 126 that is mounted to the front wall 78. A tube 128, extending into the interior of the housing, is in communication with a coating material melting and pumping unit 130 (FIG. 1). A float 131 controls the operation of the unit 130 so as to enable the unit 130 to pump coating material, as needed, into the housing interior.

A cam follower 132 is mounted on a lever 133, and the lever 133 is pivoted to the arm 48 by a pin 134. The cam follower 133 is in intersecting relationship with respect to a cam 136 that is mounted to the carriage 16. A tension spring 138, extending between the arm 48 and the lever 133, acts to yieldably urge the lever 133 clockwise (FIG. 3) against a stop 140 that is mounted to the arm 48. A clevis 142 (FIG. 4) formedon the lever 133 inwardly of the arm 48 embraces a pin 144 that is mounted to the bottom of a link 146. The top of the link 146 is rigidly connected to the housing 70 by a pin 148. A pair of tension springs 150 (FIGS. 2 and 4) extend between the tie rod 58 and the housing 70 and yieldably urge the housing clockwise (FIG. 4) about the axes of the pintles 72 with the link 146 being urged upwardly and the lever 133 being urged clockwise (FIG. 4) to a position wherein the lever 133 engages the stop 140, the springs 150 thus augmenting the spring 138.

Referring to FIGS. 2 and 3, a lever 152 is pivoted by a pin 153 to a post 154, the post 154 being bolted to the mount 10. The back of the lever 152 extends above a pin 156, the pin 156 being secured to a bracket 158 that depends from the arm 48. A tension spring 160, extending between the lever 152 and a pin 162 secured to the bracket 38, yieldably urges the back of the lever against the pin 156. A flange 164 on the front of the lever 152 acts as a carriage stop in the manner set forth below.

When the machine is running in its idle condition: the piston rod 26 is retracted into the motor 24 so that the plate 22 and the block 30 are in a lower position with the step 32 spaced from the clamp 34; the piston rod 40 is projected out of the motor 36 so that thecarriage 16 is in a forward position; the piston rod 56 is retracted into the motor 54 so that the front ends of the arms 48, 50 together with the roll 60, the housing 70 and the cam follower 132 are in a raised position and the flange 164 is in the raised position, shown in phantom in FIG. 3, in intersecting relationship with the back of the carriage 16; the motor 62 is rotating the roll 60 counterclockwise (FIG. 4); pressurized air is entering the motor 116 through a line 166 (FIG. 4) in such a manner as to urge the block 117 and the clevis 122 away from each other and thus locate the wall bottoms 81 and 88 in the FIG. 4 position wherein they are spaced from the periphery of the roll 60; the switch actuator 126 is disengaged from the switch 124; the springs 138 and 150 urge the housing 70 clockwise (FIGS. 3 and 4) about the pintles 72 to a position wherein the lever 133 engages the stop 140; and molten thermoplastic coating material is supplied from the unit 130 into the interior of the housing 70. The coating material, which is maintained in a molten viscous state in the housing 70 by electric cartridge heaters 168 (FIG. 4) in the walls 78, 84, adheres to the rotating roll 60 and forms a film on the periphery of the roll whose thickness is determined by the spacing between the wall bottom 81 and the roll periphery.

Referring to FIGS. 6 and 7, the vamp 170 of a shoe upper is placed on the block 30 in such a manner that its convergent sides are draped on the step 32 of the plate 22 below and spaced from the clamp 34. The motor 24 is now actuated to raise the piston rod 26 together with the plate 22 and the block 30 to clamp the sides of the vamp between the step 32 and the clamp 34, as seen in FIG. 6, with an exposed portion 172 of the vamp which is to be coated situated above the clamp 34.

Now the motor 36 is actuated to move the carriage 16, together with the clamped vamp 170, rearwardly under the yieldable force of pressurized air until the back of the carriage engages the flange 164 to stop the carriage in a location wherein the exposed portion of the vamp is beneath the roll 60 as indicated in FIG. 6. When the carriage 16 is stopped by the flange 164, the cam 42 is in position to shift the valve 46. The shifting. of the valve 46 causes pressurized air to enter the motor 54 so as to raise the piston rod 56 and thus swing the arms 48, 50 counterclockwise (FIG. 3). The swinging of the arms 48, 50 causes the roll 60 and the wall bottom 81 to be lowered into a position proximate to the exposed portion of the vamp 170 and causes the flange 164 to be lowered to the solid line position shown in FIG. 3 wherein 'it is out of intersecting relationship with the carriage 16. The lowering of the flange 16 enables the carriage l6 and the clamped vamp 170 to resume their rearward movement under the force of the motor 36 until the carriage and vamp reach the position shown in FIG. 7 with the roll 60 and the wall bottom 81 still in a position proximate to the exposed vamp portion 172. When the parts are in the FIG. 7 position, the cam follower 132 is located forwardly (leftwardly in F IG. 3) of the cam 136 so that the scraper blade 82 is in a relatively low position spaced close to or in contact with the top of the vamp portion 172.

Now the motor 36 is actuated to move the carriage forwardly to its starting position. During this movement, the film of thermoplastic coating material on the periphery of the roll 60 is transferred onto the exposed vamp portion 172 to form a coating 174 (FIGS. 8 and 9) on the vamp. The thickness of the coating is determined by the spacing between the scraper blade 82 and the vamp portion 172 with the scraper blade scraping off that portion of the coating material that intersects it. The scraped off coating material is returned upwardly to the interior of the housing 70 by the rotating roll 60. As the carriage 16 commences its forward movement, the cam follower 132 is moved upwardly by the cam 136 to thereby, by means of the members 142, 144, 146 and 148, swing the housing 70 clockwise (FIG. 4) about the axis of the pintles 72 and thus move the scraper blade 82 upwardly and further away from the vamp portion 172. The coating 174, as indicated in FIG. 9, therefore is of graduated thickness at one end, as indicated by the number 176.

The return of the carriage 16 to its starting position causes the cam 42 to shift the valve 44. In response to the shifting of the valve 44, the piston rod 26 is retracted into the motor 24 so as to lower the plate 22 and the block 30 and thus release the vamp 170 from the clamp 34. The shifting of the valve 44 also causes the piston rod 56 to be retracted into the motor 54, thus raising the roll 60, the housing 70, the cam follower 132 and the flange 164 to their idle positions.

The coating 174 rigidifies into a stiffener or box toe on the vamp 170 which, in a completed shoe, stiffens the toe portion of the shoe. The graduated portion 176 of the coating 174 forms the feathered edge which is desirable in box toes.

It has been found that at the end of a machine cycle a residue of coating material tends to adhere to and form a blob on the scraper blade 82. If this blob is not wiped off before the commencement of the coating operation during the forward movement of the carriage 16 in the next machine cycle, the blob can be transferred onto the vamp portion 172 forwardly (leftwardly in FIG. 8) of the front of the coating to the left (FIG. 8) of the graduated portion 176. The lowering of the scraper blade 82 by the motor 54 when the carriage 16 is in the intermediate position determined by its engagement with the flange 164 causes the blob to be wiped off the scraper blade onto the vamp portion 172 when the carriage resumes its rearward movement. Since the blob thus wiped onto the vamp portion 172 forms a part of the coating 174 that is applied to the vamp portion 172 during the subsequent forward movement of the carriage 16, the wiping ofi of the blob from the scraper blade 82 onto the vamp portion 172 does not adversely affect the coating operation.

When it is desired to shut down the machine, pressurized air is admitted into the motor 116, which constitutes an operating member, through a line 178 (FIG. 4) to urge the block 117 and the clevis 122 towards each other. Since, at this time, the pin 108 is bearing against the abutment surface 110, the block 117 and the link 98 are initially immobile and the clevis 122 is moved rearwardly so as to swing the link 90 clockwise (FIG. 4) about the pin 92 and thus swing the front wall 78 countertion between the front position and the back position wherein clockwise about the pins 80 until the wall bottom 81 engages the roll 60. The parts are so dimensioned that when the wall bottom 81 engages the roll 60 the pin 108 has swung downwardly below the abutment surface 110. Therefore, after the clevis 122 can no longer move rearwardly due to the engagement of the wall bottom 81 with the roll 60, the block 117 moves forwardly to swing the link 98 clockwise about the pin 100 with the slot 112 moving along the pin 108 and thus swings the back wall 84 clockwise about the pins 86 until the wall bottom 88 engages the roll 60. During the closing movement of the wall bottom 81 towards the roll 60, the actuator 126, which swings with the front wall 78, engages the switch 124 to shut off the motor 62 and thus stop the rotation of the roll 60. The motor 62 is so constructed that the roll 60 ceases its rotation between the engagements of the wall bottoms 81 and 88 with the roll 60.

From the foregoing it can be seen that, when the machine is shut off, first the wall bottom 81 engages the roll 60, then the roll stops its rotation and then the wall bottom 88 engages the roll. The engagement of the wall bottom with the downwardly rotating side of the roll cuts off the film of coating material on the roll periphery between the interior of the housing 70 above the roll and the wall bottom 81. The film of coating material that extends counterclockwise (FIG. 4) about the roll periphery from the wall bottom 81 to the wall bottom 88 is carried by the upwardly rotating side of the roll back into the housing interior above the roll 60. By the time the wall bottom 88 engages the stationary roll 60, there is no film on the portion of the roll periphery that extends about the bottom of the roll between the wall bottoms 81 and 88. Therefore, when the wall bottom 88 engages the stationary roll 60, all of the coating material is trapped above the roll between the wall bottoms 81 and 88 and the undesirable effects created by having coating material dripping downwardly of the stationary roll is avoided.

The seals 79 prevent leaking of the coating material between the roll 60 and the end walls 74, 76 both when the roll 60 is rotating and when the roll 60 is stationary.

lclaim:

l. A machine for applying a coating to a portion of a workpiece comprising: an applicating assembly constituted by an applicator member and a scraper member located forwardly of the applicator member; a carriage, located below the applicator assembly, mounted for forward-rearward movement; means mounting a workpiece on the carriage so that said workpiece portion is exposed for the application thereto of coating material; means mounting the applicating assembly for heightwise movement between an upper position wherein the applicating assembly is remote from said workpiece portion in a heightwise direction and a lower position wherein the applicating assembly is proximate to said workpiece portion in a heightwise direction; means for initially maintaining the carriage in a front position wherein the workpiece may be mounted to the carriage in a location that is forward of the applicating assembly; means for initially maintaining the applicating assembly in its upper position; means for moving the said workpiece portion is below the applicating assembly, for

. lowering the applicating assembly to the lower position; and

means for thereafter moving the carria e forwardly from the back position to the front position W1 the applicating assembly maintained in its lower position during the forward movement of said workpiece portion past the applicating assembly to enable the applicator member to apply a coating to the workpiece portion to a thickness determined by the spacing between the scraper member and the workpiece portion; the rearward movement of the carriage between the intermediate position and the back position enabling any blob of coating material that had previously been formed on the scraper member to be wiped onto said workpiece portion.

2. The machine as defined in claim 1 further comprising: a carriage stop mounted for heightwise movement between an upper position wherein it is in intersecting relationship with the back of the carriage and a lower position wherein it is out of intersecting relationship with the carriage; means for initially maintaining the carriage stop in its upper position so that the carriage intersects the carriage stop during its rearward movement to place the carriage in said intermediate position; and means for thereafter concomitantly lowering the applicating assembly to its lower position and lowering the carriage stop to its lower position to enable the carriage to resume its rearward movement.

3. The machine as defined in claim 2 further comprising: connections between the applicating assembly and the carriage stop so constructed as to maintain the carriage stop in its upper position when the applicating assembly is in its upper position and to lower the carriage stop to its lower position in response to the movement of the applicating assembly to its lower position.

4. An applicating mechanism comprising: a housing having a hollow interior defined by a front wall and a back wall; an applicator roll mounted for rotation in the housing between said walls with its front facing the front wall and its back facing the back wall; rotating means connected to the roll and operable to rotate it in such a manner that its front moves downwardly and its back moves upwardly; means mounting the front wall for movement towards and away from the front of the roll; means mounting the back wall for movement towards and away from the back of the roll; means for supplying coating material into the housing interior above the roll so that, when both walls are spaced from the roll and the rotating means is operating to rotate the roll, the coating material may be transferred by the bottom of the roll that is located between the bottoms of the walls onto a workpiece; an actuable operating member; and means responsive to actuation of the operating member to first move the front wall into engagement with the front of the roll, then cause the rotating means to stop the rotation of the roll, and then move the back wall into engagement with the back of the roll.

5. The mechanism as defined in claim 4 further comprising: control means, responsive to the engaging movement of the front wall towards the roll, to cause the rotating means to stop the rotation of the roll.

6. The mechanism as defined in claim 5 wherein the control means comprises: a motor control member fixedly mounted to the housing and operatively connected to the rotating means so as to stop the rotation of the roll in response to its actuation; and an actuator so mounted to the front wall as to actuate the motor control member during the movement of the front wall into engagement with the front of the roll. 

1. A machine for applying a coating to a portion of a workpiece comprising: an applicating assembly constituted by an applicator member and a scraper member located forwardly of the applicator member; a carriage, located below the applicator assembly, mounted for forward-rearward movement; means mounting a workpiece on the carriage so that said workpiece portion is exposed for the application thereto of coating material; means mounting the applicating assembly for heightwise movement between an upper position wherein the applicating assembly is remote from said workpiece portion in a heightwise direction and a lower position wherein the applicating assembly is proximate to said workpiece portion in a heightwise direction; means for initially maintaining the carriage in a front position wherein the workpiece may be mounted to the carriage in a location that is forward of the applicating assembly; means for initially maintaining the applicating assembly in its upper position; means for moving the carriage rearwardly from the front position to a back position; means, effective when the carriage is in an intermediate position between the front position and the back position wherein said workpiece portion is below the applicating assembly, for lowering the applicating assembly to the lower position; and means for thereafter moving the carriage forwardly from the back position to the front position with the applicating assembly maintained in its lower position during the forward movement of said workpiece portion past the applicating assembly to enable the applicator member to apply a coating to the workpiece portion to a thickness determined by the spacing between the scraper member and the workpiece portion; the rearward movement of the carriage between the intermediate position and the back position enabling any blob of coating material that had previously been formed on the scraper member to be wiped onto said workpiece portion.
 2. The machine as defined in claim 1 further comprising: a carriage stop mounted for heightwise movement between an upper position wherein it is in intersecting relationship with the back of the carriage and a lower position wherein it is out of intersecting relationship with the carriage; means for initially maintaining the carriage stop in its upper position so that the carriage intersects the carriage stop during its rearward movement to place the carriage in said intermediate position; and means for thereafter concomitantly lowering the applicating assembly to its lower position and lowering the carriage stop to its lower position to enable the carriage to resume its rearward movement.
 3. The machine as defined in claim 2 further comprising: connections between the applicating assembly and the carriage stop so constructed as to maintain the carriage stop in its uppeR position when the applicating assembly is in its upper position and to lower the carriage stop to its lower position in response to the movement of the applicating assembly to its lower position.
 4. An applicating mechanism comprising: a housing having a hollow interior defined by a front wall and a back wall; an applicator roll mounted for rotation in the housing between said walls with its front facing the front wall and its back facing the back wall; rotating means connected to the roll and operable to rotate it in such a manner that its front moves downwardly and its back moves upwardly; means mounting the front wall for movement towards and away from the front of the roll; means mounting the back wall for movement towards and away from the back of the roll; means for supplying coating material into the housing interior above the roll so that, when both walls are spaced from the roll and the rotating means is operating to rotate the roll, the coating material may be transferred by the bottom of the roll that is located between the bottoms of the walls onto a workpiece; an actuable operating member; and means responsive to actuation of the operating member to first move the front wall into engagement with the front of the roll, then cause the rotating means to stop the rotation of the roll, and then move the back wall into engagement with the back of the roll.
 5. The mechanism as defined in claim 4 further comprising: control means, responsive to the engaging movement of the front wall towards the roll, to cause the rotating means to stop the rotation of the roll.
 6. The mechanism as defined in claim 5 wherein the control means comprises: a motor control member fixedly mounted to the housing and operatively connected to the rotating means so as to stop the rotation of the roll in response to its actuation; and an actuator so mounted to the front wall as to actuate the motor control member during the movement of the front wall into engagement with the front of the roll. 